This invention relates to a dual light source, and more particularly to a system for automatically switching lamps in a fiber optic delivery system when the lamp being used fails in service.
Fiber optic systems for the delivery of light from a source into otherwise inaccessible locations have won widespread acceptance in a variety of situations, including their application to medical technology.
As the lamps which are utilized as the sources of light in fiber optic systems have finite lifetimes, it is readily apparent that the failure of a lamp while in service is most likely to occur during the course of a medical procedure which could be diagnostic or surgical.
In any such situation, lamp failure at best is an inconvenience, while at the other extreme such a failure at a critical point in the procedure could be dangerous to the patient.
A variety of attempts have been made to deal with this problem.
In U.S. Pat. No. 2,735,928, there is provided an emergency standby lamp which is relay activated upon failure of the filament in the primary lamp. This system could not be made applicable to a fiber optic system because there is no provision for angling the light into the end of a fiber optic termination or any other means of directing transmitted light in a specific manner.
In U.S. Pat. Nos. 3,360,640 and 3,437,803, there are disclosed surgical illuminating apparatus in which light failure is accommodated by providing multiple light sources each with its own fiber optic bundles. It is not clear nor shown how any switchover in case of bulb failure would occur.
In U.S. Pat. Nos. 3,577,173 and 4,061,911 are disclosed lamp changing mechanisms for a projector in the event of bulb failure. The standby lamp is physically moved to replace the failed lamp, and such an arrangement would inherently permit a period in which there is a loss of light, also, a mechanical arrangement is likely to be unreliable and possibly awkward in use.
In U.S. Pat. No. 4,048,486, there is provided a dual light system fed into a split fiber optic cable. With both bulbs in use, the failure of a bulb will result in light output being halved. If one lamp were being used with an automatic switchover, the beam splitter would require precision difficult to maintain to split the light exactly in half.